Such contractile units are for example disclosed in the assignee's brochure “Fluidic Muscle”, the European patent publication 0 161 750 B1, the German patent publication (utility model) 29,906,626, the German patent publication (utility model) 29,908,008 or the German patent publication (utility model) 20,112,633 and are suitable for highly exact positioning while having a simple and low-wear structure involving relatively low costs. Extremely high setting forces may be produced.
For precise positioning position sensors or angle sensors are required in principle for all servo systems. In conjunction with servo cylinders a plurality of such position sensors and sensor means is available which are based on the most various different principles of measurement. In the case of contractile units of the above noted type the same are however for the most part unsuitable or badly suited.